Dermatitis - contact
Exam Tips
- In OSCE history, separate irritant vs allergic timing: immediate/short-latency burning after irritant exposure versus delayed itch 24-72 hours after allergen re-exposure.
- Patch testing is the diagnostic gold standard for allergic contact dermatitis and is indicated when disease is persistent, recurrent, occupational, or distribution is suggestive but trigger is unclear.
- Distribution clues are high yield: finger webs/ring area in wet work, eyelids from transferred cosmetics/nail products, feet from rubber/leather/glues, ears/neck from metals/fragrances.
- State safety points in prescribing: avoid long-term potent topical steroids on thin skin; counsel paraffin fire risk; only give antibiotics when infection is clinically evident.
Definition
Contact dermatitis is an eczematous inflammatory reaction of the epidermis and superficial dermis triggered by external exposures. It is classified into irritant contact dermatitis (direct barrier injury, non-immunological) and allergic contact dermatitis (type IV delayed hypersensitivity after sensitisation), and both mechanisms may coexist in the same patient.
Pathophysiology
Irritant contact dermatitis results from repeated or high-intensity exposure to irritants (for example water, detergents, solvents, alkalis) that disrupt the stratum corneum, increase transepidermal water loss, and activate innate inflammatory pathways (keratinocyte cytokines such as IL-1 and TNF-alpha). Allergic contact dermatitis is a T-cell mediated delayed hypersensitivity reaction: small chemicals (haptens) penetrate skin, bind proteins, are presented by Langerhans cells, and on re-exposure provoke memory T-cell inflammation, typically peaking 24-72 hours later. Chronic inflammation drives lichenification, fissuring, and persistent barrier dysfunction; secondary infection can further amplify inflammation.
Risk Factors
- Wet work (frequent handwashing, prolonged glove use, repeated water exposure)
- Occupational exposure: hairdressing, beauty therapy, catering, floristry, metalwork, dentistry, healthcare cleaning/sterilising
- Exposure to common allergens: nickel/cobalt, chromate (cement), fragrances, cosmetics, hair dye (paraphenylenediamine), rubber accelerators, topical medicaments
- Repeated exposure to detergents, soaps, cleaning agents, solvents, oils, dusts, cement, bleaches (including sodium hypochlorite)
- Occlusion and sweating under PPE/gloves
- Pre-existing eczema/skin barrier impairment (increases irritant susceptibility)
- Female sex and younger adult age groups (higher exposure to jewellery/cosmetics in epidemiological studies)
Clinical Features
Symptoms
- Itch (often dominant in allergic contact dermatitis)
- Burning, stinging, smarting, tightness (common in irritant contact dermatitis)
- Dryness and chapping
- Pain from fissures in chronic hand disease
- History of flare pattern linked to exposure; occupational improvement on days off may occur
Signs
- Acute dermatitis: erythema, oedema, papules/vesicles; severe cases may blister and weep
- Chronic dermatitis: xerosis, scaling, lichenification, fissuring
- Irritant pattern often sharply limited to contact sites, with relatively spared protected skin
- Allergic pattern may extend beyond direct contact area (for example eyelid dermatitis from transferred nail products)
- Typical distributions: hands/finger webs, face/eyelids, ears, scalp, neck, axillae, feet, lower legs with dressings/topicals
- Possible secondary infection signs: crusting, purulence, spreading erythema, warmth
Investigations
Management
Lifestyle Modifications
- Identify and avoid/replace culprit exposures (fragrance-free products, nickel avoidance, workplace substitution where possible)
- Hand protection strategy: reduce wet work, use non-latex/nitrile gloves with cotton liners, avoid prolonged occlusion, dry hands thoroughly
- Regular emollient therapy as soap substitute and leave-on moisturizer (frequent application, especially after washing)
- Occupational advice: exposure diary, review PPE materials, consider occupational health input and fit-for-work adjustments
- Patient education on delayed allergic reactions (24-72 hour lag) and chronic relapse prevention
- See clinical morphology atlases/figures in standard dermatology texts (for example Rook's Textbook chapter images) to recognise pattern-based distributions in exams
Pharmacological Treatment
Emollients and barrier preparations
- White soft paraffin/liquid paraffin 50:50 ointment, applied liberally and frequently
- Urea-containing emollient 5-10% cream for hyperkeratotic dry areas (if tolerated)
First-line for all severities; continue during remission. Fire risk with paraffin-based products on clothing/bedding. May sting on fissured skin; choose acceptable formulation to improve adherence.
Topical corticosteroids for flares
- Hydrocortisone 1% cream/ointment, apply thinly once or twice daily for up to 7-14 days (mild sites such as face/flexures)
- Clobetasone butyrate 0.05% cream/ointment, once or twice daily for up to 7-14 days (moderate potency)
- Betamethasone valerate 0.1% or mometasone furoate 0.1% once daily for 7-14 days (potent for thicker hand/foot skin)
- Clobetasol propionate 0.05% once daily short course (typically 7-14 days) only for severe lichenified areas under specialist direction
Choose potency by site and severity; step down as control improves. Avoid prolonged potent steroid use on face/genitals/skin folds due to atrophy, telangiectasia, and steroid rosacea risk. Consider fingertip-unit counselling to reduce under/overuse.
Topical calcineurin inhibitors (steroid-sparing in sensitive sites)
- Tacrolimus 0.1% ointment twice daily for flares in adults, then maintenance twice weekly if recurrent
- Pimecrolimus 1% cream twice daily for mild-moderate facial/flexural disease
Useful when repeated facial/eyelid steroid courses are problematic. Avoid on clinically infected skin; photosensitivity precautions advised. Transient burning is common at initiation.
Antihistamine for nocturnal itch/sleep disturbance
- Chlorphenamine 4 mg every 4-6 hours when required (max 24 mg/day in adults)
Sedation and anticholinergic effects can impair driving and performance; use short term and counsel accordingly.
Antibiotics (only if secondary bacterial infection is present)
- Flucloxacillin 500 mg four times daily for 5-7 days (adult typical oral dose)
- Clarithromycin 500 mg twice daily for 5-7 days if true penicillin allergy and suitable
Do not use routine antibiotics for non-infected dermatitis. Check allergy status, local resistance guidance, and interaction profile (for example macrolides).
Complications
- Chronic hand dermatitis with functional impairment and occupational disability
- Sleep disturbance, reduced quality of life, and psychosocial distress/low self-esteem
- Secondary infection (impetiginisation or cellulitis)
- Post-inflammatory hypo- or hyperpigmentation
- Persistent/recurrent disease if allergen is ubiquitous or unrecognised
Prognosis
Outcome depends mainly on successful trigger identification and avoidance. Irritant dermatitis may settle quickly after exposure reduction, whereas allergic contact dermatitis is often more persistent or recurrent, especially with ubiquitous allergens (for example chromate, epoxy resin, paraphenylenediamine, Compositae plants). Poorer prognosis is associated with severe initial disease, delayed diagnosis, and continued exposure.
Sources & References
✅NICE Guidelines(1)
- Dermatitis - contact[overview]
📖Textbook References(19)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1638, 1639)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 25)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1828)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 25)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 130)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1629, 1630)[context]
- Emergencies in - Obstetrics and Gynaecology, Second Edition (Stergios K. Doumouchtsis, S. Arulkumaran) (Z-Library).pdf(pp. 313, 314)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 156)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 660)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 171, 172)[context]
- Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 173)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 644, 645)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 550, 551)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 50)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 349, 350)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 951, 952)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 949)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 923, 924)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 1274)[context]